One area that has gained a lot of interest lately is nicotinamide adenine dinucleotide (NAD+), a coenzyme responsible for cell metabolic activity and energy production, and its role in slowing down the physical and mental changes of aging. We know that NAD+ decreases as we get older—but we also know you can support your levels through supplementation. This includes the buzzy nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) supplements. While they both support the production of NAD+, there are differences in how they work and the science behind them. Some studies on rodents2 also suggest that NMN may work better for certain conditions, such as age-related cognitive decline. But in terms of human clinical studies, Sommer White, M.D., an integrative and functional medicine physician, says “NR has the most evidence to back up its effectiveness.” Here is a summary of what we know about these two supplements. NR can be found naturally in food: “Milk3 and yeast products are a source of NR,” says White, and milk also contains other NAD+ precursors in smaller amounts. However, he doesn’t recommend using these as your source since the volume you’d have to consume to get the benefits would be too great. NR supplements are much more effective at supporting NAD+ levels in the body. The research bears out NR supplement use—several human clinical trials of NR supplements have been completed, including randomized placebo-controlled trials (RCTs), the “gold standard” of clinical research. In one eight-week study4, researchers found that people taking NR had an increase in their blood NAD+ levels. Healthy overweight adults tolerated a daily oral NR dose of up to 1,000 milligrams, with no flushing or serious side effects. Another study5 showed that NR is more bioavailable, or has better absorption, than nicotinamide and nicotinic acid. Scientists are not certain how NMN gets into the cells1. It may be transported directly or may require more cofactors—such as vitamins and antioxidants—to make the process work smoothly. NMN occurs naturally in various foods. The highest amounts are found in edamame, broccoli, cucumber, and cabbage. Moderate amounts are present in avocado and tomato. Smaller amounts show up in raw beef, shrimp, cow milk, and human breast milk8. Because of a the low levels of NMN in these foods, NMN supplements may be a more effective way to increase levels and a few NMN supplements are currently available. Most studies on the safety of NMN have been done in rodents9. Only one safety study of NMN10 done in people has been published. In this clinical trial, researchers found that a single dose of up to 500 mg of NMN didn’t cause any serious side effects. Several clinical trials of NMN in the United States and other countries are currently underway or recently completed.
